An unrestricted duty does not automatically become make-up performance merely because a self-selected date has passed. Valid fulfilment remains performance of the original obligation.
Adāʾ is discharge of the duty in the legally relevant mode; qaḍāʾ becomes especially pertinent when a legally designated performance window has passed.
For example, moving a personally planned expiation from Thursday to Friday does not by itself turn it into “making up” an expired legal period.
The continuing existence of the duty must still be distinguished from the separate issue of responsibility for any delay.